Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

University of Massachusetts Amherst

Theses/Dissertations

2016

Articles 61 - 81 of 81

Full-Text Articles in Physical Sciences and Mathematics

A Haptic Surface Robot Interface For Large-Format Touchscreen Displays, Mark Price Jul 2016

A Haptic Surface Robot Interface For Large-Format Touchscreen Displays, Mark Price

Masters Theses

This thesis presents the design for a novel haptic interface for large-format touchscreens. Techniques such as electrovibration, ultrasonic vibration, and external braked devices have been developed by other researchers to deliver haptic feedback to touchscreen users. However, these methods do not address the need for spatial constraints that only restrict user motion in the direction of the constraint. This technology gap contributes to the lack of haptic technology available for touchscreen-based upper-limb rehabilitation, despite the prevalent use of haptics in other forms of robotic rehabilitation. The goal of this thesis is to display kinesthetic haptic constraints to the touchscreen user …

Go to article

Designing Active Granular Squares, Christopher C. Olson Jul 2016

Designing Active Granular Squares, Christopher C. Olson

Masters Theses

The goal of this thesis has been to find a means of i) designing an active square particle, and ii) continuously varying its degree of activity with the objective of understanding the effects of activity on the various phases of granular matter. The motivations, results and limitations of our methods of creating active particles are discussed in this thesis. The applicability of a stochastic model based on the Langevin equation in 2D as well as implications for future experiments are also discussed.

Go to article

A Comparative Sustainability Study For Treatment Of Domestic Wastewater: Conventional Concrete And Steel Technology Vs. Vegetated Sand Beds (Vsb’S) And Their Relative Differences In Co2 Production, Alicia M. Milch Jul 2016

A Comparative Sustainability Study For Treatment Of Domestic Wastewater: Conventional Concrete And Steel Technology Vs. Vegetated Sand Beds (Vsb’S) And Their Relative Differences In Co2 Production, Alicia M. Milch

Masters Theses

Conventional wastewater treatment in the U.S. is an energy dependent and carbon dioxide emitting process. Typical mechanical systems consume copious amounts of energy, which is most commonly produced from fossil fuel combustion that results in the production of CO2. The associated organic load is also metabolized by microorganisms into CO2 and H2O. As the desire to reduce CO2 output becomes more prominent, it is logical to assess the costs of conventional treatment methods and to compare them to alternative, more sustainable technology. Vegetated Sand Bed (VSB) and Reed Bed (RB) systems are green technologies …

Go to article

Micropaleontology And Isotope Stratigraphy Of The Upper Aptian To Lower Cenomanian (~114-98 Ma) In Odp Site 763, Exmouth Plateau, Nw Australia, Ali Alibrahim Jul 2016

Micropaleontology And Isotope Stratigraphy Of The Upper Aptian To Lower Cenomanian (~114-98 Ma) In Odp Site 763, Exmouth Plateau, Nw Australia, Ali Alibrahim

Masters Theses

The biostratigraphy and isotope stratigraphy of the upper Aptian to lower Cenomanian interval including oceanic anoxic events OAE1b, 1c and 1d are investigated in ODP Site 763, drilled on the Exmouth Plateau offshore northwest Australia. Benthic foraminifera suggest that Site 763 was situated in outer neritic to upper bathyal water depths (~150-600 m). OAEs of the Atlantic basin and Tethys are typically associated with organic carbon-rich black shales and δ13C excursions. However, OAEs at this high latitude site correlate with ocean acidification and/or pyrite formation under anoxic conditions rather than black shales. Ocean acidification maybe responsible for sporadic …

Go to article

Invasive Species Occurrence Frequency Is Not A Suitable Proxy For Abundance In The Northeast, Tyler J. Cross Jul 2016

Invasive Species Occurrence Frequency Is Not A Suitable Proxy For Abundance In The Northeast, Tyler J. Cross

Masters Theses

Spatial information about invasive species abundance is critical for estimating impact and understanding risk to ecosystems and economies. Unfortunately, at landscape and regional scales, most distribution datasets provide limited information about abundance. However, national and regional invasive plant occurrence datasets are increasingly available and spatially extensive. We aim to test whether the frequency of these point occurrences can be used as a proxy for abundance of invasive plants. We compiled both occurrence and abundance data for nine regionally important invasive plants in the northeast US using a combination of herbarium records, surveys of expert knowledge, and various invasive species spatial …

Go to article

Shape Design And Optimization For 3d Printing, Yahan Zhou Mar 2016

Shape Design And Optimization For 3d Printing, Yahan Zhou

Doctoral Dissertations

In recent years, the 3D printing technology has become increasingly popular, with wide-spread uses in rapid prototyping, design, art, education, medical applications, food and fashion industries. It enables distributed manufacturing, allowing users to easily produce customized 3D objects in office or at home. The investment in 3D printing technology continues to drive down the cost of 3D printers, making them more affordable to consumers. As 3D printing becomes more available, it also demands better computer algorithms to assist users in quickly and easily generating 3D content for printing. Creating 3D content often requires considerably more efforts and skills than creating …

Go to article

Oceanic Anoxia Event 2 (~94 Ma) In The U.S. Western Interior Sea: High Resolution Foraminiferal Record Of The Development Of Anoxia In A Shallow Epicontinental Sea, Amanda L. Parker Mar 2016

Oceanic Anoxia Event 2 (~94 Ma) In The U.S. Western Interior Sea: High Resolution Foraminiferal Record Of The Development Of Anoxia In A Shallow Epicontinental Sea, Amanda L. Parker

Masters Theses

The Upper Cretaceous Tropic Shale of southern Utah captures critical oceanographic changes that occurred during Oceanic Anoxic Event 2 (OAE 2) and the transgression of the Greenhorn Sea. We investigated the response of planktic and benthic foraminifera in a shallow (<100 >m) marine environment stressed by the onset of OAE 2 during the Cenomanian-Turonian boundary (CTB; 93.9 Ma) to determine the oceanographic mechanisms controlling the observed turnovers in the foraminiferal record. This study is based on high-resolution quantitative foraminifera counts and isotope paleoecology (d18O and d13C) from a 40-m outcrop. The OAE 2 interval is identified …

Go to article

Sources Of Water And Solutes To The Salar De Atacama, Chile: A Coupled Hydrologic, Geochemical, And Groundwater Modeling Study, Lilly G. Corenthal Mar 2016

Sources Of Water And Solutes To The Salar De Atacama, Chile: A Coupled Hydrologic, Geochemical, And Groundwater Modeling Study, Lilly G. Corenthal

Masters Theses

Focused groundwater discharge in endorheic basins provides opportunities to investigate mechanisms for closing hydrologic budgets in arid regions. The Salar de Atacama (SdA), a closed basin in northern Chile, has accumulated over 1800 km3 of halite and a lithium-rich brine since the late Miocene primarily through evapotranspiration of groundwater. The hydrologic balance of SdA and sources of water and solutes required to explain this deposit are not well constrained. An adapted chloride mass balance method drawing on a database of over 200 water sample sites is applied to a remotely-sensed precipitation dataset to estimate spatially-distributed modern groundwater recharge. Comparing …

Go to article

Design Of Romp-Based Protein Mimics For Sirna Delivery, Brittany M. Deronde Mar 2016

Design Of Romp-Based Protein Mimics For Sirna Delivery, Brittany M. Deronde

Doctoral Dissertations

Designing delivery agents for therapeutics is an ongoing challenge. As treatments and desired cargoes become more complex, the need for improved delivery vehicles becomes critical. Excellent delivery vehicles must ensure the stability of the cargo, maintain the cargo’s solubility, and promote efficient delivery and release. In order to address these issues, many research groups have looked to nature for design inspiration. Proteins, such as HIV-1 TAT and Antennapedia homeodomain protein, are capable of crossing cellular membranes. However, due to the complexities of their structures, they are synthetically challenging to reproduce in the laboratory setting. Being able to incorporate the key …

Go to article

Topology Of The Affine Springer Fiber In Type A, Tobias Wilson Mar 2016

Topology Of The Affine Springer Fiber In Type A, Tobias Wilson

Doctoral Dissertations

We develop algorithms for describing elements of the affine Springer fiber in type A for certain 2 g(C[[t]]). For these , which are equivalued, integral, and regular, it is known that the affine Springer fiber, X, has a paving by affines resulting from the intersection of Schubert cells with X. Our description of the elements of Xallow us to understand these affine spaces and write down explicit dimension formulae. We also explore some closure relations between the affine spaces and begin to describe the moment map for the both the regular and extended torus action.

Go to article

Stimuli Responsive Polymer Self-Assembly And Disassembly, Jiaming Zhuang Mar 2016

Stimuli Responsive Polymer Self-Assembly And Disassembly, Jiaming Zhuang

Doctoral Dissertations

Stimuli responsive polymer assemblies have been long investigated for drug application due to their flexibility for surface functionalization to achieve desired interfacial property and capability of acting as a host for payloads encapsulation. These interfacial and host-guest properties are very critical and need to be customized really depending on nature of cargos and specific delivery application. More importantly, these properties are always desired to be adaptable in different environments. For instance, adjustable interfacial property can facilitate the carrier to overcome a variety of different barriers before it reach the target while changeable host-guest property allows to selectively releasing the payload …

Go to article

Self-Assembly And Stimuli Responsive Disassembly Of Dendritic And Oligomeric Amphiphiles, Krishna Reddy Raghupathi Mar 2016

Self-Assembly And Stimuli Responsive Disassembly Of Dendritic And Oligomeric Amphiphiles, Krishna Reddy Raghupathi

Doctoral Dissertations

Stimuli response is a fundamental process prevalent in all living systems, where a specific function (response) is generated in the presence of a given environmental cue (stimulus). Engineering materials for this process is often accomplished through another basic process, “self-assembly”. By understanding the key aspects of these processes scientists have developed a broad range of materials for a wide array of applications. This dissertation will primarily focus on developing stimuli responsive nanocarriers based on supramolecular assemblies of amphiphilic dendrimers and oligomers for safe transport and selective release of molecular cargo. Our concurrent goal is to also investigate several parameters which …

Go to article

Translocations Of Ring And Linear Polymers & Polyelectrolyte Brush In Salty Solution, Ning Ouyang Mar 2016

Translocations Of Ring And Linear Polymers & Polyelectrolyte Brush In Salty Solution, Ning Ouyang

Doctoral Dissertations

We study the electric-field-driven translocation of polymers with ring architecture, i.e. circular polymers, in comparison with their linear counterpart. We construct the free energy landscape for ring and linear polymer translocations respectively, in the context of Fokker-Planck formalism. Non-monotonicity of translocation time as function of polymer length is observed from ring polymer, which is enhanced by pore- polymer attraction. The external electric driving force and pore-polymer interaction are the tuning parameter of relative translocation time of ring and linear polymers. We study the polyelectrolyte brush in monovalent salt using self-consistent-field- theory. We confirmed the step-function polymer profile in strong-stretched state. …

Go to article

Equivariant Intersection Cohomology Of Bxb Orbit Closures In The Wonderful Compactification Of A Group, Stephen Oloo Mar 2016

Equivariant Intersection Cohomology Of Bxb Orbit Closures In The Wonderful Compactification Of A Group, Stephen Oloo

Doctoral Dissertations

This thesis studies the topology of a particularly nice compactification that exists for semisimple adjoint algebraic groups: the wonderful compactification. The compactifica- tion is equivariant, extending the left and right action of the group on itself, and we focus on the local and global topology of the closures of Borel orbits. It is natural to study the topology of these orbit closures since the study of the topology of Borel orbit closures in the flag variety (that is, Schubert varieties) has proved to be inter- esting, linking geometry and representation theory since the local intersection cohomology Betti numbers turned out …

Go to article

Algorithms For First-Order Sparse Reinforcement Learning, Bo Liu Mar 2016

Algorithms For First-Order Sparse Reinforcement Learning, Bo Liu

Doctoral Dissertations

This thesis presents a general framework for first-order temporal difference learning algorithms with an in-depth theoretical analysis. The main contribution of the thesis is the development and design of a family of first-order regularized temporal-difference (TD) algorithms using stochastic approximation and stochastic optimization. To scale up TD algorithms to large-scale problems, we use first-order optimization to explore regularized TD methods using linear value function approximation. Previous regularized TD methods often use matrix inversion, which requires cubic time and quadratic memory complexity. We propose two algorithms, sparse-Q and RO-TD, for on-policy and off-policy learning, respectively. These two algorithms exhibit linear computational …

Go to article

Refractive Index Engineering And Optical Properties Enhancement By Polymer Nanocomposites, Cheng Li Mar 2016

Refractive Index Engineering And Optical Properties Enhancement By Polymer Nanocomposites, Cheng Li

Doctoral Dissertations

The major part of this dissertation discusses the engineering of the refractive index of materials using solution-processable polymer nanocomposites and their applications in building optical components and devices. Three particular polymer nanocomposites have been introduced to achieve materials with tunable refractive indices and enhanced optical properties, which can be used to manipulate the behavior of light or electromagnetic radiations. In the first system, polyhedral oligomeric silsesquioxane (POSS)/polymer nanocomposites are developed. Thin films with tunable, low refractive indicies were fabricated from the composites. The mechanical strength of these films was characterized, and their application in antireflective coatings is discussed. In the …

Go to article

(I) Polymer Nanocomposites: Rheology And Processing For Mesoporous Materials And (Ii) Nanopatterning Of Metal Oxides Using Soft Lithography, Rohit Kothari Mar 2016

(I) Polymer Nanocomposites: Rheology And Processing For Mesoporous Materials And (Ii) Nanopatterning Of Metal Oxides Using Soft Lithography, Rohit Kothari

Doctoral Dissertations

The research in this dissertation is categorized into two parts. The first part is focused on investigation of order-to-disorder transitions (ODT) in nanocomposites of an amphiphilic block copolymer containing various hydrogen-bonded additives, and fabrication of novel mesoporous silica based materials by utilizing such nanocomposites as templates. Disordered Pluronic®, poly(ethylene oxide) (PEO)−poly(propylene oxide) (PPO)−PEO triblock copolymer upon blending with small molecule additives containing hydrogen-bond-donating functional groups (carboxyl or hydroxyl) result into ordered nanoscale morphologies by preferentially interacting with the hydrophilic PEO chains in the Pluronic®. The dependence of ODT-temperature in these novel Pluronic®/small-molecule-additive complexes on composition, number and type of functional …

Go to article

Voltage Driven Translocation Of Polyelectrolytes Through Nanopores, Byoung-Jin Jeon Mar 2016

Voltage Driven Translocation Of Polyelectrolytes Through Nanopores, Byoung-Jin Jeon

Doctoral Dissertations

Recently, translocations of polyelectrolyte molecules through membrane channel protein pores or solid-state nanopores have been actively studied. Although the polymer translocation researches emerged mainly due to technological demands in terms of genome sequencing, the detailed physics of the single molecule transport through a narrow channel remains fully understood. To obtain further understanding of common features of the translocation process, this thesis focuses on the effects of salt concentration, pore-polymer electrostatic interactions, and externally applied electric field on the voltage-driven polymer translocations. The study is carried out by performing a series of systematically designed experiments using alpha-hemolysin (αHL) protein pore to …

Go to article

Supramolecular Strategies For The Generation Of Nanoparticle Assemblies And Biomolecular Thin Films, Bradley P. Duncan Mar 2016

Supramolecular Strategies For The Generation Of Nanoparticle Assemblies And Biomolecular Thin Films, Bradley P. Duncan

Doctoral Dissertations

The conceptual framework of supramolecular chemistry elucidates a powerful set of strategies for chemists to generate functional nanomaterials based on intermolecular forces. My research focused on tuning the molecular interactions of nanoscale components to create larger structures with enhanced properties. In one approach, I developed and optimized an additive-free, nanoimprint lithography-based methodology to generate stable thin films from a variety of proteins. The generalized process retains intrinsic properties of the protein as demonstrated by selective cellular adhesion. The heat and pressure of the nanoimprinting process induces slight structural reorganization of the peptide side chains to yield highly stable films held …

Go to article

Modeling, Analysis And Numerical Simulations In Mathematical Biology Of Traveling Waves, Turing Instability And Tumor Dynamics, Mei Duanmu Mar 2016

Modeling, Analysis And Numerical Simulations In Mathematical Biology Of Traveling Waves, Turing Instability And Tumor Dynamics, Mei Duanmu

Doctoral Dissertations

The dissertation includes three topics in mathematical biology. They are traveling wave solutions in a chain of periodically forced coupled nonlinear oscillators, Turing instability in a HCV model and tumor dynamics. Motivated by earlier studies of artificial perceptions of light called phosphenes, we analyze traveling wave solutions in a chain of periodically forced coupled nonlinear oscillators modeling this phenomenon. We examine the discrete model problem in its co-traveling frame and systematically obtain the corresponding traveling waves in one spatial dimension. Direct numerical simulations as well as linear stability analysis are employed to reveal the parameter regions where the traveling waves …

Go to article

The Application Of Hydrogen/Deuterium Exchange And Covalent Labeling Coupled With Mass Spectrometry To Examine Protein Structure, Nicholas B. Borotto Mar 2016

The Application Of Hydrogen/Deuterium Exchange And Covalent Labeling Coupled With Mass Spectrometry To Examine Protein Structure, Nicholas B. Borotto

Doctoral Dissertations

Thorough insight into a protein’s structure is necessary to understand how it functions and what goes wrong when it malfunctions. The structure of proteins, however, is not easily analyzed. The analysis must take place under a narrow range of conditions or risk perturbing the very structure being probed. Furthermore, the wide diversity in size and chemistry possible in proteins significantly complicates this analysis. Despite this numerous methods have been developed in order to analyze protein structure. In this work, we demonstrate that mass spectrometry (MS)-based techniques are capable of characterizing the structure of particularly challenging proteins. This is done through …

Go to article

First Prev